WALTHAM -- Celtics guard Avery Bradley will travel with the team to Detroit but is "doubtful" for Sunday's game against the Pistons, according to Doc Rivers.

Bradley suffered sore ribs during Wednesday's game against the New Orleans Hornets and did not play Friday against the Chicago Bulls.

"I think he's going to get another x-ray because he didn't improve," Rivers said before practice on Saturday. "I think he's there now getting an x-ray. They just want to make sure they're not cracked or something like that. I think the x-rays showed it wasn't, but maybe do a deeper one just to make sure."

A team official later announced those x-rays came back negative.

Bradley made his season debut on January 2 after rehabbing from double shoulder surgery. Eight games later, he was back on the sidelines.

While Rivers would prefer to have Bradley in the lineup, he understands injuries are part of the game for an athletes who competes so physically.

"He just plays hard and guys like that are going to get injured," said Rivers. "That's fine by me, it really is. I want him to play the way he plays. He'll probably get better at it as his career goes on, and have less and less. But (Anderson) Varejao gets hurt all the time, he plays hard. There's a group of guys. Delonte (West),&nbsp; Kirk Hirnich is one of those guys. He's always in the scrum. But you can't do without those guys, either, and what they do is really important for your team so you would never tell them not to."

Bradley is averaging 8.1 points, 1.5 rebounds, and 1.3 assists per game. The Celtics went on a six-game winning streak during his first eight games back.